Kinetic properties of polyphenoloxidase in organic solvents A study in Brij 96‐cyclohexane reverse micelles

Abstract

Polyphenoloxidase entrapped in Brij 96-cyclohexame reverse micelles showed both cresolase activity towards monophenols and catecholase activity towards diphenols. The kinetic parameters, such as apparent K,,,, temperature effect and pH profile, were determined for catecholase activity, the findings being very close to those found in aqueous systems. The enzyme activity was dependent on the molecular ratio of water to surfactant (o,), obtaining a maximum activity at o, = IO. The stability of the system with time increased with the water content until W, = 10, and then decreased. An inverse relation was found between activity and water volume fraction (6)

Reverse vesicles as a new system for studying enzymes in organic solvents

“…The enzyme concentration used in each medium was 1.5 ,tg/ml. [7]. 0.5 t Activity measured in Brij 96/cyclohexane reverse micelles (JW.…”

“…Polyphenol oxidase activity was also measured in 50 mM-Mes buffer, pH 6.0, at 20°C and in Brij 96/cyclohexane reverse micelles [water/surfactant molar ratio (W.) = 12] by using previously described methods [7,9].…”

“…The present paper aims to show for the first time that such reverse vesicles are capable of entrapping enzymes without any loss in enzyme activity. The enzyme used was polyphenol oxidase (EC 1.14.18.1), as this oxidase has been assayed in other surfactant structures, such as liposomes [6] and reverse micelles, by our group [7][8][9].…”

Increased activity of Chromobacterium viscosum lipase in AOT reverse micelles in the presence of short chain methoxypolyethylene glycol

“…To overcome this problem, the addition of some non‐ionic surfactants such as Tween 85 (polyoxyethylene sorbitan trioleate) to the AOT reverse micellar systems was proposed and proved to be very effective by a number of researchers9–13 and also by our group 14. It has been shown that Tween 85 effectively reduces the surface charge density and the hydrophobicity of AOT reverse micelles by adsorption at the water–oil interface 12–14…”

Oxidation Catalysis by Enzymes in Microemulsions

“…Tyrosinase is an enzyme that has drawn attention due to its application in enzyme biosensors for the detection of phenolic pollutants. This enzyme is one of the first that has been proven to function in reversed micelles, such as those formed by AOT surfactant in isooctane [91], cyclohexane [92], and hexane [93] and others composed of nonionic Brij96 (poly-(10)-oxyethylene oleyl ether) in cyclohexane [94]. Yang and Robb [95] studied two different microemulsions composed of AOT and isooctane and CTAB, hexane and chloroform, where mushroom tyrosinase was immobilized and effectively used to catalyze the formation of o-quinones by oxidation of o-diphenols and presented superactivity in AOT microemulsion.…”